Document FR-A-2 587 667 describes a device giving easy access to rail vehicles while stopped at a station and including a doorsill and a board forming a loading ramp. The doorsill and the board are hinged between two extreme positions: a folded position in which the vehicle can run, and an unfolded position giving access to the vehicle. In the folded position, the doorsill is in a horizontal position and constitutes a portion of the floor of the vehicle. In the unfolded position, the doorsill and the board are inclined, with the board resting against the platform.
Given its structure and function, that device, when in the unfolded position, has a slope of about 20%. Such a high figure is no longer acceptable, and railway operators are now tending to set a maximum figure of 10%. In addition, the housing for the device in the vehicle occupies a large amount of vertical space that requires a cutout to be formed in the vehicle frame. This reduces the strength of the frame and consequently it reduces passenger safety. Finally, the device includes a hinged doorsill which, while the vehicle is running, constitutes a source of draughts and gives rise to problems of sealing. As a result, the device cannot be used in high speed trains whose access doors are fitted with inflatable gaskets for combatting phenomena due to pressure waves.
A device of the same kind is described in FR-A-35 2 416 136. That device comprises an access ramp to the vehicle and capable of moving between a retracted position in which its outer portion constitutes a conventional type of step, and an extended position enabling handicapped people to gain access to the vehicle. The device also includes members for controlling the extending and retracting movements of the access ramp. That device suffers from the same drawbacks as those specified for document FR-A-2 587 667.